Neurodegeneration associated with brain iron accu ulation (N BIA) comprises a heterogeneous group of disorders, such as infantile neuroaxoal dystroph (INAD), in which disruption of cellular mechanisms leads to accumulation of iron in the b sal ganglia. This group includes patients with discovered mutations in the PLA2G6 gene that enc des group VI Ca '-independent phospholipase A, (iPLA2 or iPLA2P). Recently, more and more patien with INAD were identified containing mutations in the PLA2G6 gene, designated as PLA2G6-asso iated Neurodegeneration (PLAN). Our broad longterm goal is to characterize the molecular and ceHu ar mechanisms by which dysfunction of iPLA2 leads to neurodegeneration associated with brain iron accumulation in PLAN. iPLA2 catalyzes hydrolysis of sn-2 acyl chains from phospholipids a d plays an important role in cell membrane homeostasis and trafficking. Recently it was report d that iPLA2-knockout mice recapitulate the neurodegenerative features of human INAD. Little i known about how alteration of iPLA2 function causes brain iron accumulation. Previously we rep rted that inhibition of iPLA2 results in the increase of cell-membranous phosphatidylcholines containin polyunsaturated fatty acid residues that induces phosphorylation of p53 through activation of ataxia- elangiectasia mutated and Rad3-related (ATR). We have identified that hepcidin, a hormone regula ing iron export, is activated by inhibition of iPL~ in a p53 dependent manner. These findings allow u to hypothesize that dysfunction of iPLA, leads to a p53-mediated induction of hepcidin expression, ich in turn causes degradation of iron exporter ferroportin, ablation of the iron cellular export, and i on accumulation in the brain of NIBA. In this twoyear ARRA award , our objectives are: 1) to determine the expression of hepcidin in the brains of iPLA2-KO mice using in situ hybridization, 2) to det rmine the effects of mutants of iPLA2 on hepcidin expression in primary iPLA2 -I- neural cells, 3) to ch racterize p53-dependent transcriptional expression of hepcidin in the primary iPLA2 -1- neural cells, and 4) to examine the expression of hepcidin, ferroportin , and ferritin in the brain sectio s of iPLApound'-/p53-'- mice. Achieving this proposal's goals will explain why dysfunction of iPLA2 causes i on accumulation in iPLArKO mice and in INAD patients. In addition, the ARRA funding for this proj ct will preseve jobs, which will significantly contribute to the improvement of our local economy.

Public Health Relevance

Although brain iron accumulation has been identified in the genetic childhood neuroaxonal dystrophies as well as in the Parkinson disease an Alzheimer disease for many years, the molecular and cellular mechanisms underlying iron accumula ~o n are poorly understood. This study will significantly advance our understanding of the path genesis of neurodegeneration with brain iron accumulation and may provide novel insights into t e development of therapeutic protocols capable of attenuating the disease process in humans.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
1R01NS063962-01A1
Application #
7728107
Study Section
Neural Oxidative Metabolism and Death Study Section (NOMD)
Program Officer
Gwinn, Katrina
Project Start
2009-08-01
Project End
2011-07-31
Budget Start
2009-08-01
Budget End
2010-07-31
Support Year
1
Fiscal Year
2009
Total Cost
$381,375
Indirect Cost
Name
Icahn School of Medicine at Mount Sinai
Department
Other Health Professions
Type
Schools of Medicine
DUNS #
078861598
City
New York
State
NY
Country
United States
Zip Code
10029
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Ma, Zhongmin A (2012) The role of peroxidation of mitochondrial membrane phospholipids in pancreatic ? -cell failure. Curr Diabetes Rev 8:69-75
Ma, Zhongmin Alex; Zhao, Zhengshan; Turk, John (2012) Mitochondrial dysfunction and ?-cell failure in type 2 diabetes mellitus. Exp Diabetes Res 2012:703538
Zhao, Zhengshan; Wang, Jing; Zhao, Chunying et al. (2011) Genetic ablation of PLA2G6 in mice leads to cerebellar atrophy characterized by Purkinje cell loss and glial cell activation. PLoS One 6:e26991
Zhao, Zhengshan; Zhang, Xu; Zhao, Chunying et al. (2010) Protection of pancreatic beta-cells by group VIA phospholipase A(2)-mediated repair of mitochondrial membrane peroxidation. Endocrinology 151:3038-48